We have the same problem. We were told we need to replace some part or other, but, sorry, I'm not sure what part. We are having it done at Independence RV in FL. in the fall. In the meantime, we are using the burner. We have had problems off and on with the Oasis unit in our 2008 Dutch Star from the start, although we have talked to others who get plenty of hot water when set on just AC 1. We have tried on AC1 and AC1&2, to no avail. If I find out the name of the part, I will post it.